Device for separating petri dishes



3,228,857 Patented Jan. 11, 1966 ice 3,228,857 DEVICE FOR SEPARATENGPETRI DISHES James McCormick, La Grange, Ill., assignor, by mesneassignments, to Ames Lab-Tali, Inc., a corporation of MassachusettsFiled Nov. 20, 1962, Ser. No. 239,020 4 Claims. (Cl. 195139) Thisinvention relates to petri dishes conventionally used for the growth ofcultures and the like and, in particular, to an improved device forpositioning a petri dish and a cover relative to one another so as tofacilitate the cooling of nutrients within the dish while shielding thenutrient from atmospheric contamination.

Petri dishes are relatively shallow containers which are adapted to befilled with a normally solid nutrient material, such as agar-agar, whilethe nutrient is in a hot liquid state. Normally, the dishes containingthe nutrient are then left standing in either a partially or totallyuncovered condition to allow the nutrient to cool and solidify before aculture to be studied or grown is added. The practice heretofore hasbeen to place the cover in partially overlying relation to the dish soas to expose the nutrient to the atmosphere and facilitate the coolingand solidification thereof, while at the same time shielding a portionof the nutrient from a direct exposure to the atmosphere and therebyreduce the amount of dust and foreign particles which would normallysettle on the surface of the nutrient and contaminate it.

The partial covering of the petri dish with its cover does notcompletely solve the problem of contamination of the nutrient, since avertical entry into the interior of the dish by descending dust andgerms is still possible. Additionally, the cover is unstable when it isonly partially covering the dish, and can be easily displaced to aposition in which it no longer covers the nutrient, or covers it socompletely as to prevent an efiicient dissipation of heat from thenutrient. Either of these results is undesirable, particularly When anattempt is being made to grow a series of cultures under substantiallyidentical conditions.

It is, therefore, the principal object of this invention to provide animproved device for separating a petri dish from an overlying coveringmeans.

A still further object of the invention is to provide an improved devicefor separating a petri dish from an overlying cover, which deviceincludes means for aligning the dish and cover and for preventingaccidental displacement of the cover.

An additional object of this invention is to provide a device forseparating a petri dish from its cover, which device is economical toproduce and easy to use.

It is another object of this invention to provide an improvedcombination of petri dish, cover and separating device, whichcombination reduces the likelihood of entry of dust and foreignparticles into the interior of the petri dish.

Other objects more or less ancillary to the foregoing will be easilyperceived from the following detailed description and drawings, inwhich:

FIGURE 1 is a perspective view of a device showing various of thefeatures of the invention;

FIGURE 2 is a side elevation of the device of FIG. 1;

FIGURE 3 is an enlarged section along line 3-3 of FIG. 1;

FIGURE 4 is a sectional view showing the device as it appears whenseparating a petri dish and cover; and

FIGURE 5 is a sectional view similar to that of FIG. 4, but showing theuse of two such devices in the separation and support of two stackablepetri dishes.

In general, the present invention relates to a device for spacing andaligning a petri dish cover with respect to an underlying petri dish.

Referring now to the drawings in detail, there is shown in FIG. 1 adevice 60 for spacing and aligning a cover with respect to a petri dish.The device includes three equal length rod-like side members 62 whichare interconnected to form a planar body of generally triangularconfiguration. The side members are relatively thin, preferably having athickness of approximately 0.125 inch, and are of a length such thateach of the apeXes of the triangle formed by the side members extendsbeyond the side wall of a petri dish when the device is centrallypositioned on the dish and its side members are resting on the upperedge of the dish.

Although other shapes are contemplated, the triangular shaped device, asshown by FIG. 1, is considered to be particularly advantageous. Thetriangular shape imparts rigidity to the device. Additionally, thetriangular shaped device forms the largest possible opening between theouter edge of the rods 62 and the inner wall of the dish, through whichopening heat may be dissipated.

Flanges 64 are integrally connected to the device 60 at the points ofinteresection of members 62, each of the flanges lying in a planegenerally normal to the plate defined by the side members 62. As bestseen in FIG. 2, each of the flanges 64 has an arcuate upper portion 66disposed above the plane of the side members 62 and an arcuate lowerportion 68 disposed below the plane of the side members.

As seen in FIG. 4, the flanges 64 are arranged so as to define a spacejust large enough to receive a petri dish cover, the flanges 64 being inclose proximity to the side wall of the cover when the cover is disposedso as to rest upon the upper surface of the side members.

As shown in FIG. 3, the portions 66 and 68 of flange 64 are of lesserthickness toward their extremities to facilitate the insertion andremoval of a petri dish cover from the space defined by the flanges 64.

Since the dish is of a lesser diameter than the cover, there will not bea snug fit between the device and the dish. The flanges act to align thedevice on the dish and they also prevent an accidental lateraldisplacement of the cover or device relative to the underlying dish.

Tabs 70 are integrally attached perpendicular to the flanges 64 and areadapted to be grasped by the fingers in order that the device, as wellas any covers or dishes supported by the device, can be easily picked upand handled. The tabs 7% can conveniently be made the same thickness asthe flanges 64 and of a convenient length such as one-half inch.

The device can be made from any suitable material, such as glass orplastic, but is preferably constructed of plastic. Any plastic ofsufiicient strength and durability can be employed and the device can beformed by any suitable method, such as molding or casting.

In use, and as shown in FIG. 4, the device 60 is placed on a dish 72with the depending portions 68 of the flanges 64 aligning the device onthe dish. A cover 74 is then placed on the device within the spacedefined by the upstanding portion of the flanges. Due to the triangularshape of the device, the side members 62 lie across the space defined bythe dish, and the cover rests upon the side members 62 and not upon thedish, thereby spacing the cover from the dish a distance equivalent tothe thickness of the side member.

The device of the present invention is particularly adapted for use withs-tackable petri dishes, such as those described and in the co-pendingapplication of James B. McCormick, Serial No. 207,896, filed July 6,1962 now U.S. Patent No. 3,198,713, issued August 3, 1965. Stackahlepetri dishes are particularly desirable where counter 3 space is at apremium since many petri dishes can be conveniently and safely stackedin the space formerly required for one such dish.

The petri dish described in the aforementioned Patent No. 3,198,713 isshaped similar to those petri dishes illustrated by FIG. 5. Each dishhas a depending lip or flange '76 of a size and configuration that itfits over the side wall 78 of another of the dishes. Thus, each dishalso acts as a cover for another dish when the dishes are stacked in themanner disclosed in such patent. The interfitting of the sidewall of onedish and the lip of another dish gives the stack suflficient rigiditythat there is little danger of the stack being knocked down.

The device of the present invention can be placed between each of thestackable petri dishes in a manner similar to that shown in FIG. 5.After a number of dishes have been stacked in this manner, a singlecover can be placed on the uppermost device 60. This gives a completelysterile stack of petri dishes in which dust and other contaminants areexcluded from all the dishes, but in which heat may be dissipatedreadily through a horizontal passageway leading from the interior ofeach of the dishes. When the dishes have cooled and the culture has beenplaced in the dish, the devices 60 are removed and the dishes arestacked in a normal manner.

The device, as described and illustrated in the accompanying drawing,performs the dual functions of providing a convenient and easy to usemethod of separating petri dishes from their covers, and of aligning thecover with respect to the underlying dish so that the only access orexit to the interior of the dish will be a horizontal openingapproximately the width of the side members of the device. By limitingthe access to the interior of the dish to a horizontal opening, anuncontaminated dust-free culture is obtained.

The sterility of the dish and cover, and in particular the cover, isalso improved by the use of the device since they need not be handledonce they are assembled with the device. The provision of the fingertabs on the flanges allows the device to be readily picked up. When acover and dish are used in combination substantially as shown in FIG. 4,it can be seen that the cover can be remove-d from the dish by liftingthe device by grasping the finger tabs extending from the flanges. Thedepending portions of the flanges then act as legs and form a stableplatform which can be used to support a cover, or, if desired, a petridish, off the surface of the table or counter, thus keeping the cover ordish from coming into contact with contaminants that might be present onthe surface of the table or counter. Additionally, the dependingportions of the flanges act to keep the portion of the device whichoverlie the dish from contacting the table or counter.

It can be seen from the foregoing that an improved device for use withpetri dishes has been provided, as well as an improved combination of apetri dish, cover and device which acts to efficiently prevent thecontamination of the petri dish by dust or other particles settling outof the air onto the interior of the dish. At the same time, theprovision of the device between the cover and dish allows air to passfreely into the interior of the dish between the cover and the dish. Adevice has been provided which is easily handled and which positivelyaligns the cover with respect to the dish.

Various of the features of the invention are set forth in the followingclaims.

What is claimed is:

1. In combination, a petri dish for receiving goods, a cover for saiddish adapted to substantially sea-l said dish from the atmosphere, and adevice interposed between said dish and cover to space said cover fromsaid dish and facilitate the cooling of the contents of the dish, saiddevice comprising a planar body portion formed from at least three sidemembers interconnected at their ends, flanges connected to said body atthe points of in- 4 tersection of said members, said flanges extendingabove and below said body in a direction generally normal thereto, and atab carried by at least one of said flanges adapted to be grasped by thefingers.

2. In combination, a petri dishv for receiving goods, a cover for saiddish adapted to substantially seal said dish from the atmosphere, atriangularly shaped device interposed between said dish and said coverso as to facilitate dissipation of heat from goods disposed in saiddish, said device comprising a planar body portion formed from threerod-like side members of equal length interconnected at their ends,flanges integrally connected to said body at the points of intersectionof said members, said flanges extending above and below said body in adirection generally normal thereto and defining a space just largeenough to receive said cover, and a tab carried by at least one of saidflanges adapted to be grasped with the fingers, whereby said devicealigns said cover relative to said dish.

3. A device for use in separating and aligning a petri dish and covercomprising, a triangular planar body portion having three rod-like sidemembers of equal length rigidly connected to one another at theirextremities, flanges integrally connected to said body at the points ofintersection of said members, said flanges extending above and belowsaid body in a direction generally normally thereto, said flanges beingso spaced from one another that the inner surfaces thereof define acircle of predetermined diameter closely approximate to the diameter ofthe petri dish cover, the extremities of said flanges having a decreasedthickness and an arcuate shape and defining a space just large enough toreceive a petri dish and cover, whereby the device, cover and petri dishare held in alignment when in an assembled form, and a tab carried by atleast one of said flanges adapted to be grasped with the fingers, saidtab lying generally in the plane of said planar body portion andextending from the side of said one flange outside said triangular bodyportion.

4. A device for use in separating and aligning a petri dish and cover,which device comprises a planar body including at least three rod-likeside members of equal length rigidly connected to one another at theirextremities, flanges integrally connected to said body at the points ofintersection of said members and lying generally normal to the plane ofsaid body, said flanges extending above and below the plane of saidbody, said flanges being so spaced from one another that the innersurfaces thereof define a circle of predetermined diameter closelyapproximate to the diameter of a petri dish cover, whereby, whendisposed between an underlying petri dish and an overlying cover, thedevice maintains the petri dish and cover in substantially coaxialalignment and also prevents lateral displacement of the cover from thepetri dish while spacing the dish and cover vertically apart, and a tabwhich is integral with said planar body and which lies generally in theplane thereof, said tab extending from the outside of the perimeter ofsaid planar body a sulficient distance outside the circumference of saidcircle of predetermined diameter to adapt said tab to be easily graspedwith the fingers.

References Cited by the Examiner UNITED STATES PATENTS 815,883 3/1906Blarcom 195-139.01 2,361,992 11/1944 Cantor 195139.0l 2,391,466 12/1945Levin 23-292 2,526,259 10/1950 Moch.

. 3,097,070 7/1963 Aldrich l139.01

OTHER REFERENCES Aloe Scientific Equipment Catalogue No. 103 received inUS. Patent Oflice March 3, 1953, p. 444.

A. LOUIS MONACELL, Primary Examiner.

1. IN COMBINATION, A PETRI FOR RECEIVING GOODS, A COVER FOR SAID DISH ADAPTED TO SUBSTANTIALLY SEAL SAID DISH FROM THE ATMOSPHERE, AND A DEVICE INTERPOSED BETWEEN SAID DISH AND COVER TO SPACE SAID COVER FROM SAID DISH AND FACILITATE THE COOLING OF THE CONTENTS OF THE DISH, SAID DEVICE COMPRISING A PLANAR BODY PORTION FORMED FROM AT LEAST THREE SIDE MEMBERS INTERCONNECTED AT THEIR ENDS, FLANGES CONNECTED TO SAID BODY AT THE POINTS OF INTERSECTION OF SAID MEMBERS, SAID FLANGES EXTENDING ABOVE AND BELOW SAID BODY IN A DIRECTION GENERALLY NORMAL THERETO, AND A TAB CARRIED BY AT LEAST ONE OF SAID FLANGES ADAPTED TO BE GRASPED BY THE FINGERS.
 3. A DEVICE-FOR USE IN SEPARATING AND ALIGNING A PETRI DISH AND COVER COMPRISING, A TRIANGULAR PLANAR BODY PORTION HAVING THREE ROD-LIKE SIDE MEMBERS OF EQUAL LENGTH RIGIDLY CONNECTED TO ONE ANOTHER AT THEIR EXTREMITIES, FLANGES INTEGRALLY CONNECTED TO SAID BODY AT THE POINTS OF 